A wide variety of nondestructive techniques are used to gather data and to provide condition assessment reports for industrial components. Standards for such examinations are defined by organizations such as the American Society for Nondestructive Testing (ASNT), the American Society for Testing of Materials (ASTM), the American Society for Mechanical Engineering (ASME), the American Welding Society (AWS), the International Standards Organization (ISO) and other national and international entities. Nondestructive examination techniques are available for the inspection of surface conditions (e.g. dimensional measurement and visual inspection), for the inspection of near-surface and surface-opening conditions (e.g. dye penetrant test, magnetic particle test and thermography), and depending upon the material of construction of the component, for full volumetric inspection (e.g. eddy current test, ultrasonic test, radiographic test).
Experience shows that a majority of the information and data available for diagnostics and prognostics, and the data most directly relatable to the assessment of component condition, comes from visual inspections and dimensional measurements. There may be over one hundred visual examinations and inspections required during the manufacturing and service life of a typical gas turbine component, for example.
To augment traditional manual visual inspections it is known to utilize the capabilities of modern optical imaging devices together with computers and software in systems often referred to as aided visual inspections.